﻿using System;
using System.Collections.Generic;
using System.Linq;
using System.Text;
using System.Threading.Tasks;

namespace ConsoleApp1
{
    class Program
    {
        static void Main(string[] args)
        {
            const Double PI = 3.14;
            int r = 5;
            Console.WriteLine("圆的周长是："+ 2 * PI * r);
            Console.WriteLine("圆的面积是：" + PI * r * r );

            int num = 5;
            if (num > 7)
            {
                Console.WriteLine("大于7");
                
            }
            else if (num > 8)
            {
                Console.WriteLine("大于8");
            }
            else 
                    {
                Console.WriteLine("送货速度花费大概都会佛啊大哥哈都i规划");
            }


            int points = 95;
            switch (points / 10)
            {
                case 9:
                    Console.WriteLine("优秀");
                    break;

                case 8:
                    Console.WriteLine("良好");
                    break;
                case 7:
                    Console.WriteLine("及格");
                    break;
                


            }




        }
    }
}



